Generation of x-ray radiation in a plasma created by a train of pulses from a regenerative СО$_2$ amplifier

For the first time an investigation was made of the generation of hard x-ray radiation ($\hslash\omega\approx$ 3 – 5 keV) in a plasma of Dural and tungsten targets created by a regenerative СО$_2$ amplifier with moderate laser radiation intensities of $\sim10^{10}$ – $10^{11}$ W/cm$^2$. It was found that, even at such relatively low СО$_2$ laser radiation intensities in the plasma, instabilities can develop which generate hot superthermal electrons responsible for hard x-ray emission. The experimental results are discussed.